Rybakina will be joined by fellow top-10 players Jessica Pegula, Elina Svitolina, Iga Swiatek and Marta Kostyuk in a tournament that could have significant implications for the race to qualify for the WTA Finals.
The Tokyo event takes place as the season reaches its final stages, with players chasing valuable ranking points and one of the last opportunities to strengthen their positions in the PIF Race to the WTA Finals.
Svitolina and Karolina Muchova currently occupy sixth and seventh place, respectively, in the standings, while Linda Noskova is eighth. Noskova has the added security of having won a Grand Slam this season, meaning she would need to fall below No. 20 in the standings to miss qualification.
Kostyuk and Swiatek are currently ninth and 10th, respectively, with the second-to-last WTA 1000 tournament of the season in Beijing getting underway.
The Tokyo field also features a host of players ranked inside the world's top 20, including Belinda Bencic, Iva Jovic, Diana Shnaider, Sorana Cirstea, Naomi Osaka, Alexandra Eala, Elise Mertens and Jasmine Paolini.
Cirstea's appearance could carry added significance, with the tournament potentially being the final event of her career.
The remaining direct entrants are Maja Chwalinska, Anna Kalinskaya, Leylah Fernandez and Ekaterina Alexandrova. Ann Li, Diane Parry, Maria Sakkari and Nikola Bartunkova are the first four players listed as main-draw alternates.
The 28-player main draw will consist of 17 direct entrants, six qualifiers, four wild cards and one special-exempt place. The top four seeds will receive first-round byes.
Bencic returns as defending champion
Bencic returns to Tokyo as the defending champion after winning the title last year.
The Swiss player defeated Varvara Gracheva, Muchova and Sofia Kenin on her way to the final, where she beat Noskova to claim the championship.
The upcoming tournament will be Bencic's seventh appearance at the Toray Pan Pacific Open. She made her debut in Tokyo in 2013 and reached the final two years later, losing to Agnieszka Radwanska.
Osaka, meanwhile, will return to a tournament where she has enjoyed considerable success. The Japanese star won the title in 2019 and also reached the final in 2016 and 2018.
Rybakina will arrive in Tokyo with another major objective in addition to winning the tournament. The Kazakh is also competing for the year-end world No. 1 ranking.
She reached the semifinals in Tokyo last year after winning her opening two matches, but withdrew from her semifinal because of back pain.
Valuable points up for grabs
With the WTA season approaching its conclusion, the Tokyo tournament could prove important for players seeking to strengthen their rankings and improve their chances of reaching the WTA Finals.
The tournament's champion will earn 500 ranking points and $185,500 in prize money.
First-round action is scheduled to begin on Monday, October 26, with the tournament concluding on Sunday, November 1, when both the singles and doubles champions will be crowned.
With a deep field featuring several top-ranked players and contenders for the season-ending championships, Tokyo will provide one of the final major opportunities of the WTA season for players to make their case on the court.